ABSTRACT
In 1948 Lockwood classified congenital anomalies of the gallbladder into three basic types: anomalies of location, number, and form. Of these, anomalies of form had the largest number of different subtypes. This category of variants includes various kinds of gallbladder folding, septations, unusual gallbladder shapes, and the uncommon gallbladder diverticulum, bilobed gallbladder, and rudimentary gallbladder. A junctional fold appears as a linear filling defect on oral cholecystography or as a dense or echogenic line on computed tomography. The Phrygian cap is a specific type of gallbladder fold. A dilated common bile duct can be simulated by a tortuous or redundant gallbladder neck. The valves of Heister are spiral folds or mucous membrane projections that line the cystic duct and gallbladder neck. While small millimeter-sized folds are normal in the gallbladder, true septations are uncommon. Possible etiologies include: a congenital mucosal diaphragm that results from incomplete cannulation of the lumen at development; adenomyomatosis, which develops on a congenital diaphragm, or both.
